Triangle button sticking down slightly

The triangle button on my 5 day old controller is sticking down slightly (half pressed). The other buttons (x, square and circle) also semi sticking but not as bad.

I have searched online and most answers say it dirt in the controller but how can this be if it's a new device which I have only used for 6-7 hours total? (I always have clean hands and don't eat food when playing)